Delicate products, i.e. products which tend to perish quickly, for example including liquids such as milk or beer, are made to be long-lasting by means of pasteurization, that is to say by heating above a certain limit temperature, wherein harmful germs contained in the product or liquid are killed during the pasteurization.
In order to achieve a sufficient pasteurization of the filled product to be pasteurized, a certain number of pasteurization units must be administered to this filled product. If this number is not reached, the durability of the product is negatively impaired; if this number is exceeded, the taste of the filled product may be impaired, which is likewise extremely undesirable. The number of pasteurization units is a function of the actual temperature of the product and the time span during which the product is at this actual temperature.
Pasteurizers are generally known. The pasteurizers of interest here are used to pasteurize a continuous product chain. To this end, such a pasteurizer has a heat-up region, a pasteurization region and a cooling region, wherein the products rest on a transport means by which they are transported through the regions in the abovementioned sequence from the inlet to the outlet of the pasteurizer, wherein the products are heated up, pasteurized and cooled in the respective regions.
The transport means is for example a modular belt.
The individual treatment regions are subdivided into zones in the direction of motion of the products.
For the purpose of heat transfer, the products are sprayed from above with a temperature-controlled spray medium, for example water. The spray medium is at different temperatures in the individual zones, the temperature being adapted to the respectively desired type of treatment, i.e. heating up, pasteurization or cooling of the products. For dispensing the spray medium, spray nozzles from which the spray medium exits are arranged above the transport plane of the containers.
In pasteurizers according to the prior art, such as for example that known from EP 89 911 538.0, the open-loop or closed-loop control of such a pasteurizer and also of the pasteurization process takes place in that the conveying speed of the transport means and/or the temperature of the spray medium is changed in at least one treatment zone.
One feature common to all known pasteurizers is that, at least within each individual treatment zone, the volumetric flow rate of the spray medium, measured in cubic meters per hour and square meter of treatment area (m3/(h*m2)], is either zero—the spray is thus switched off—or else remains constant. It should be noted that, to date, there have been disclosed only pasteurizers in which the volumetric flow rate is the same in all the treatment zones of a pasteurizer.
On account of these circumstances, the known prior art thus suffers from the disadvantage that pasteurizers or the pasteurization process, in the event of changes in the operating state, for example in the event of fault-induced interruptions, fluctuations in the number or products per unit time, etc., can be changed or adapted only by changing the process parameters transport speed and temperature of the spray medium in individual treatment zones, which considerably restricts the possibilities for optimal adjustment or control of the pasteurizer or of the pasteurization process.